A majority of the prior art disclosures relating to retention catheters are improvements or modifications of the well known and widely used Foley catheter, all of which, in use, interpose a balloon between the lowermost portion of an associated bladder and a drainage eye at the distal tip.
Other prior art includes catheters having interiorly disposed balloons, the inflation thereof either moving a portion of the enclosed balloon to an exterior position or expanding the end portion of the catheter; the inflation of the balloon in each of these structures causing the appearance of drainage openings into the drainage lumen of the catheters.
Catheters having tips extending beyond the balloon often cause trauma from pressure of the tip, thus creating an area of inflammation which on subsequent cystoscopy may require biopsy for assurance that no malignancy is present. Also, there is always the hazard of the protruding tip causing disruption of suture lines such as those following surgery on the bladder. Further, the drainage eyes, being normally positioned above the lowermost space of the cavity, are not in position to enable complete drainage. The undrained fluid becomes stagnant, encouraging infection, pain and delayed healing.
An important consideration in the construction of any inflatable balloon catheter is the provision of means for monitoring the position of the balloon with respect to the passageway leading to the cavity to be drained, to avoid the hazard attending the inflation of the balloon within the passageway, e.g., the urethral canal. Previously described catheters having drainage eyes at the tip and associated retracted balloons are obviously susceptible to such hazardous procedures; this is also true of catheters having retracted drainage eyes which are caused to appear in response to the inflation of an associated balloon.